A cyst is an abnormal pocket of fluid, like a blister, that can form in many different areas of the body, including the skin, genitals and internal organs. A cyst is one of the most serious type of pimples. When blocked pores get irritated, they may form cysts, which can become filled with a whitish-yellow liquid called pus, sometimes causing pain. Infections, tumors, parasite and injuries can cause cysts. Cysts are usually noncancerous.
A cyst will not heal until it’s lanced and drained or surgically excised by a physician. Without treatment, cysts will eventually rupture and partially drain.
If you’re concerned about a cyst, The Art of Skin Dermatology offers 
